Currently, this project involves studies on the interactive effects of stimulation of the dopamine system and impairment of the olfactory system on the social behavior of male hamsters. It has been found that apomorphine, a putative activator of dopamine receptors, greatly inhibits copulatory behavior and increases aggressive behavior in sexually active male hamsters. Apomorphine also increases aggression in olfactory bulbectomized males, indicating that the drug acts independently of the normal olfactory sensory control of aggression in hamsters. The only animals failing to show a response to apomorphine were four males in which lesions of the sensory nerve supplying the accessory olfactory bulbs had temporarily eliminated mating behavior. BIBLIOGRAPHIC REFERENCES: Murphy, M.R.: Blinding increases territorial aggression in male Syrian golden hamsters. Behavioral Biology 17: 139-141, 1976. Murphy, M.R.: Olfactory stimulation and olfactory bulb removal: Effects on territorial aggression in male Syrian golden hamsters. Brain Research, 113: 95-110, 1976.